The field of the invention generally relates to household refrigerators, and more particularly relates to humidity control mechanisms for crisper pans.
Most household refrigerators have one or more pans for storing fresh vegetables and fruits. These pans are typically referred to as crisper pans and their function is to create a storage environment that has a higher humidity than the rest of the refrigerated food compartment. Accordingly, in crisper pans, vegetables and particularly leafy vegetables do not dry out so fast as they would if stored uncovered in the relatively low humidity of the refrigerated food compartment.
A prior art crisper pan typically has side support lips that slidably engage guide channels on the underside of a shelf which also provides a lid for the crisper pan. When the crisper pan is slid to the closed position, the pan is completely sealed underneath the shelf. As a result, the cold, dry air circulating in the refrigerated food compartment is prevented from flowing through the pan; accordingly, the interior of the pan is maintained at a relatively high humidity. Stated differently, by providing a tight seal for the pan, moisture in the vegatables is prevented from escaping the pan to the rest of the refrigerated food compartment. Some prior art crisper pans have also used gaskets to improve the seal.
The prior art shows a recognition that too much moisture in a crisper pan may adversely affect vegetables and fruit. For example, if a large quantity of very moist vegetables is placed in a crisper pan, the very high humidity in the pan may cause condensation which drips down and forms puddles. It is well known that a soggy condition can cause vegetables to wilt or rot. Accordingly, it is known that it may be desirable to adjust or control the humidity in a crisper pan to a preferable range depending on the food load wherein the humidity is high enough to prevent the food from drying out, but is low enough to prevent excessive condensation.
One prior art approach to crisper pan humidity control is described in U.S. Pat. No. 4,013,434 to Kronenberger et al. The cover of the crisper pan has a plurality of side vents running longitudinally from front-to-back. A manual control includes a damper and integral hinge pin with cooperating arcuate fingers extending through the vents, which fingers have surfaces for engaging edge portions of their associated vents to impart positioned stability in any one of a plurality of angularly related positions. The damper has a front tab for manually rotating the damper to any of the plurality of angular positions between fully closed and fully open. A disadvantage of this approach is that it doesn't have cooperating openings on opposing edges of the cover to take advantage of flow-through ventilation. Also, the location of the vents on the sides doesn't take advantage of the natural flow path of recirculating air. More specifically, the cold air flow path of most refrigerators is down the back wall, across the bottom, and then up the front wall. A side vent, on the other hand, does not directly face this flow path. As a rsult, relatively poor control of humidity is provided.
In another approach described in U.S. Pat. No. 4,250,719 to Grimm et al, a crisper pan has a top opening and a stationary cover inside the refrigerator for receiving the pan. Within the stationary cover is a lid having inclined ribs on the underside. Lateral movement of a slide control at the front of the crisper is transformed into forward or backward movement of the lid. In the backward position, the lid rides up onto the ribs thereby elevating it from the crisper pan. Accordingly, openings are provided around the top of the crisper pan and the size of these opening can be varied by the position of the crisper pan relative to the lid. This apparatus, however, has disadvantages. First, the lid does not also function as a shelf because the operative principle requires the lid be vertically movable to adjust the humidity; accordingly, the lid is an extra part that is mounted under the bottom shelf. Not only does this involve extra cost and more complicated fabrication, but it also reduces available refrigerator storage space. Further, the parts and fabrication for an apparatus that transforms movement in one direction to orthogonal motion is generally more complicated and expensive than one that does not. Further, the apparatus is subject to sticking and breaking. Also, because the recirculating air may also leak out the sides, there may be nonuniform humidity in the crisper pan from front-to-back.
Another prior art approach is described in U.S. Pat. No. 4,557,118 to Pink. A back passageway into the crisper pan is alway open, and a front passageway is controlled by a laterally slidable shutter member. Although this arrangement provides many advantages, it is difficult to maintain high humidity with certain food loads because the back passageway always remains open.